Study On Microstructure And Properties Of High Performance Fe Based Amorphous Composite Coating By Plasma Cladding

Surface amorphous technology is to prepare a certain thickness of amorphous coating on the surface of mechanical parts through surface engineering technology,so as to improve the strength,hardness and wear resistance of mechanical parts.This technology has considerable potential application in the field of material modification.Surface amorphization on mechanical parts by cladding technology can effectively improve the comprehensive properties of materials?strength,hardness and wear resistance?,prolong the service life of mechanical parts and reduce production costs.However,the research on amorphous cladding surface has not made breakthrough progress,and there is a lack of comprehensive and systematic understanding of the influencing factors and forming rules of surface amorphous,so this study has very important academic and application value..In this paper,the amorphous composite coatings of Fe₆₀Cr₁₆Nb₁₂Mo₅Si₂B₅?wt%?and trace element C and La₂O₃ were prepared on 45 steel substrate by one-step plasma cladding technology assisted by self-made water-cooling circulating system.The effects of cladding parameters?cladding current and cladding speed?on phase composition,amorphous content,macro-forming and micro-structure of the coating were systematically studied.The optimum parameters were obtained as cladding current 110A and cladding speed 6mm/s.The microstructure,microhardness,thermal stability,wear resistance and erosion resistance of the coatings were studied and analyzed by means of various characterization and testing methods?XRD,SEM,TEM,DSC and friction and wear tester,etc.?.The results show that the Fe-based amorphous composite coatings have good metallurgical bonding with the matrix under the optimum technological parameters,and the surface quality and properties are obviously better than those of the matrix.The crystalline phases in the coating are mainly composed of acicular martensite and lower bainite.According to the fitting calculation of TEM,XRD and Pseudo-Voigt function,amorphous phase existed in the coating and amorphous content reached 13.46%.In addition,a small amount of micro-particles Mo₂B and Fe₂B compound existed.The coating prepared by the best process 110A-6mm/s has high thermal stability and the glass transition temperature Tg is 733.5°C;The microhardness of the coating reaches 1000HV_0.3¹100 HV_0.3;The coating has excellent wear resistance,and the wear mechanism of the coating is mainly adhesive wear and oxidative wear.At the impact angle of 30 degrees,the erosion forms of the substrate and coating are mainly impact,cutting and furrows.It was found that the addition of C increased the formation of amorphous phase in the alloy system by adding C and La2O3.The amorphous phase content was 15.15%when C was added2%.When C is increased from 1%to 2%,the microhardness of the coating is the highest,up to1280HV_0.3.The wear resistance is the best when C content is 2%.The wear mechanism of the coating is mainly oxidation wear,abrasive wear and adhesion wear.The addition of La2O3promotes the formation of more amorphous phases.When the La2O3 content is 2%,the microhardness is 1000HV0.3.When the content of La2O3 is 1%and 2%,the wear resistance is the best.The wear mechanism of the coating is mainly oxidation wear,abrasive wear and delamination wear.